[ping-sender] adding missing doxygen tags (#6330)

doc/ot_api_doc.h

@@ -57,6 +57,7 @@
  * @defgroup api-icmp6                ICMPv6
  * @defgroup api-ip6                  IPv6
  * @defgroup api-srp                  SRP
+ * @defgroup api-ping-sender          Ping Sender
  * @defgroup api-udp-group            UDP
  *
  * @{

include/openthread/instance.h

@@ -53,7 +53,7 @@ extern "C" {
  * @note This number versions both OpenThread platform and user APIs.
  *
  */
-#define OPENTHREAD_API_VERSION (86)
+#define OPENTHREAD_API_VERSION (87)
 
 /**
  * @addtogroup api-instance

include/openthread/ping_sender.h

@@ -45,6 +45,16 @@
 extern "C" {
 #endif
 
+/**
+ * @addtogroup api-ping-sender
+ *
+ * @brief
+ *   This file includes the OpenThread API for the ping sender module.
+ *
+ * @{
+ *
+ */
+
 /**
  * This structure represents a ping reply.
  *
@@ -105,6 +115,11 @@ otError otPingSenderPing(otInstance *aInstance, const otPingSenderConfig *aConfi
  */
 void otPingSenderStop(otInstance *aInstance);
 
+/**
+ * @}
+ *
+ */
+
 #ifdef __cplusplus
 } // extern "C"
 #endif